Hardcoded field coords in defense_utils.py and defense_strategy.py

[energy-in-joles]

hardcoded field coords preventing FieldDimensions from being fully customisable.

[energy-in-joles]

is this fixed? @fred-huang122

[fred-huang122]

is this fixed? @fred-huang122

It's now using custom fields but there is still some issues with the goalie algorithm. I was planning to haveNingchuan and Yanping to help me have a look at it for me.